This invention relates to a laminated layer type fuel cell and, more particularly, to the configuration of channels of a gas separation plate or an electrode substrate.
FIG. 1 is a perspective view showing a prior-art laminated layer type fuel cell disclosed, for example, in Japanese Patent Application Laid-open No. 58-163181. In FIG. 1, numeral 1 designates a gas separation plate, in which rectilinear fuel channels 1a and oxidizer channels 1b of rectangular-shaped cross section are formed in perpendicular directions to one another on the upper and lower surfaces of the gas separation plate 1. Numeral 2 designates cells which are each formed of a fuel electrode, an electrolyte matrix and an oxidizer electrode mounted in operation between the two gas separation plates 1. A laminated layer type fuel cell includes the gas separation plates 1 and the cells 2 sequentially laminated one after another. Arrows A and B respectively designate the directions of flow of the fuel and the oxidizer.
The operation of the laminated layer type fuel cell will be explained herebelow.
The fuel and the oxidizer supplied to the fuel channels 1a and the oxidizer channels 1b, respectively, are converted by the electrochemical reaction of the cells 2 into electric power. The current supplied by the cell reaction depends upon the partial pressures of the reaction components in the fuel and the oxidizer and increases as the partial pressures are higher.
Since the prior-art laminated layer type fuel cell is constructed as described above, the current varies according to the cell reaction which depends upon the partial pressures of the fuel and the oxidizer reaction gases. For example, since the partial pressure of the reaction gases are high in the portions corresponding to the fuel and oxidizer inlets of the fuel channels 1a and the oxidizer channels 1b, the flowing current is large. On the contrary, since the reaction gases are being consumed along the channels, at the upstream side of both channels, the partial pressures of the reaction gases decrease (i.e. especially in the portions corresponding to the fuel and oxidizer outlets of the fuel channels 1a and the oxidizers channels 1b), resulting in a small current. Accordingly, there arises problems that the electrochemical reaction in the cells become uneven with the result that the temperature distribution in the cells become irregular.